Package org.opensourcephysics.numerics

Class Util

java.lang.Object
org.opensourcephysics.numerics.Util
public final class Util extends Object
A utility class for numerical analysis. This class cannot be subclassed or instantiated because all methods are static.
Version:
1.0
Author:
Wolfgang Christian

  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    static final double
    defaultNumericalPrecision
    The default precision for numerical analysis.
    static final double
    LOG10
     
    static final double
    SQRT2PI
     

  • Method Summary

    Modifier and Type
    Method
    Description
    static int
    checkSorting(double[] array)
    Checks if an array is sorted.
    static double
    computeAverage(double[] array, int start, int num)
    Computes the average value of a subset of an array.
    static Function
    constantFunction(double c)
    Creates a function having a constant value.
    static double
    evalMath(String str)
    Evalautes a mathematical expression without variables.
    static String
    f2(double d)
    Convert a double to a string, printing two decimal places.
    static String
    f3(double d)
    Convert a double to a string, printing three decimal places.
    static String
    f4(double d)
    Convert a double to a string, printing four decimal places.
    static double[]
    functionFill(Function f, double start, double stop, double[] data)
    Fills the given double[n] array with f(x) on the interval [start, stop].
    static double[][]
    functionFill(Function f, double start, double stop, double[][] data)
    Fills the given double[2][n] array with x and f(x) values on interval [start, stop].
    static Function
    gaussian(double x0, double sigma)
    Creates a Guassian (normal) distribution function.
    static double[]
    getRange(Function f, double a, double b, int n)
    Gets the approximate range of a function within the given domain.
    static Function
    linearFunction(double m, double b)
    Creates a linear function with the given slope and intercept.
    static DecimalFormat
    newDecimalFormat(String format)
     
    static void
    newSpinnerNumberModel(JSpinner spinner, int value, int min, int max, int step)
     
    static double
    relativePrecision(double epsilon, double result)
    Computes the relativePrecision except near zero where the absolute precision is returned.

    Methods inherited from class java.lang.Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

  • Field Details

    • SQRT2PI

      public static final double SQRT2PI

    • LOG10

      public static final double LOG10

    • defaultNumericalPrecision

      public static final double defaultNumericalPrecision
      The default precision for numerical analysis.

  • Method Details

    • newDecimalFormat

      public static DecimalFormat newDecimalFormat(String format)

    • f2

      public static String f2(double d)
      Convert a double to a string, printing two decimal places.
      Parameters:
      d - Input double

    • f3

      public static String f3(double d)
      Convert a double to a string, printing three decimal places.
      Parameters:
      d - Input double

    • f4

      public static String f4(double d)
      Convert a double to a string, printing four decimal places.
      Parameters:
      d - Input double

    • relativePrecision

      public static double relativePrecision(double epsilon, double result)
      Computes the relativePrecision except near zero where the absolute precision is returned.
      Parameters:
      epsilon - the absolute error
      result - the result
      Returns:
      the relative error

    • checkSorting

      public static int checkSorting(double[] array)
      Checks if an array is sorted. Returns: Positive integer if array is sorted in increasing value. Negative integer if array is sorted in decreasing value. Zero if array is not sorted.
      Parameters:
      array - double[]
      Returns:
      int 1,0,-1 based on sorting

    • getRange

      public static double[] getRange(Function f, double a, double b, int n)
      Gets the approximate range of a function within the given domain. The range is deterermiend by evaluating the function at n points and finding the minimum and maximum values.
      Parameters:
      f - Function
      a - double
      b - double
      n - int
      Returns:
      double[]

    • functionFill

      public static double[][] functionFill(Function f, double start, double stop, double[][] data)
      Fills the given double[2][n] array with x and f(x) values on interval [start, stop].
      Parameters:
      f - Function
      start - double
      stop - double
      data - double[][]
      Returns:
      double[][]

    • functionFill

      public static double[] functionFill(Function f, double start, double stop, double[] data)
      Fills the given double[n] array with f(x) on the interval [start, stop].
      Parameters:
      f - Function
      start - double starting value of x
      stop - double stopping value of x
      data - double[]
      Returns:
      double[]

    • computeAverage

      public static double computeAverage(double[] array, int start, int num)
      Computes the average value of a subset of an array.
      Parameters:
      array - the data to be averaged
      start - the index of the first point to be averaged
      num - the total number of points to be averaged
      Returns:

    • constantFunction

      public static Function constantFunction(double c)
      Creates a function having a constant value.
      Parameters:
      c -
      Returns:

    • linearFunction

      public static Function linearFunction(double m, double b)
      Creates a linear function with the given slope and intercept.
      Parameters:
      m - double slope
      b - double intercept
      Returns:
      Function

    • gaussian

      public static Function gaussian(double x0, double sigma)
      Creates a Guassian (normal) distribution function. The distribution is normalized. The full width at half maximum is 2*sigma*Math.sqrt(2 Math.log(2)) ~ 2.3548*sigma
      Parameters:
      x0 - double center of the distribution
      sigma - double width of the distributuon
      Returns:
      Function

    • evalMath

      public static double evalMath(String str)
      Evalautes a mathematical expression without variables.
      Parameters:
      str - String
      Returns:
      double

    • newSpinnerNumberModel

      public static void newSpinnerNumberModel(JSpinner spinner, int value, int min, int max, int step)